1. Field
The invention relates to an improved head capable of writing and reading audio, video and digital data onto and from a magnetic medium, and particularly to write/read heads utilizing the single wall domain (bubble) concept to perform wideband recording and playback of signals without requiring mechanical movement or high head-to-tape speeds, and with no limitation on the signal-to-noise ratio by the recording process.
2. Prior Art
The recording and readout of wideband signals requires a write/read system which has very high head-to-tape speed and includes systems with mechanical motion. Such prior art systems include rotary head recording, longitudinal tape recording, and straight high speed or direct video recording, wherein head-to-tape velocities lie in the range of 1000 to 2000 inches per second (ips). All these systems require contact between the recording medium and the head, which causes problems of medium and head wear due to high impact of the head against the tape. In addition, such systems have various mechanical and electronic problems associated with the medium transports, particularly in the area of speed servoing of not only the tape, but also the heads, as in the rotary head type of video recording system.
Such mechanical prior art video recording systems are also closely approaching the maximum densities possible by present state-of-the-art magnetic head techniques and materials, while advances in recording densities are possible with regards to the state-of-the-art of present and future magnetic recording mediums. Thus, present prior art video recording systems will not be able to take advantage of the improved density capabilities expected from future magnetic recording mediums.
Bubble write heads utilizing stray fields generated by a bubble in a bubble material are shown, for example, in U.S. Pat. Nos. 3,793,639 to U.E. Enz et al and 3,739,640 to J.A. Potgiesser. Such devices show that the stray field from a bubble can be used to record analog or digital information on a magnetizable medium. Such recording can be accomplished either with or without the aid of a magnetic bias field, dependent upon the strength of the stray field obtainable from the bubble. Prior art devices typified by the above patents suffer from several limitations. For example, the recording process is continuous, i.e., the stray field from a bubble continuously writes on the magnetic medium to define an uninterrupted track of reversed magnetization. Therefore, to record information, either the size or the location of the magnetized track must be varied. This prevents use of logic and control bubble circuits within the device, since the bubbles in these circuits would also write tracks on the magnetic medium thereby distorting and/or destroying the tracks containing the desired information. The requirement to vary the width or the location of a track in order to record information increases the effective width of each track and thus reduces the track density. Further, these devices are write heads only and are not capable of reading the recorded information.